William j



"wLF. LAUGHRAN AND i 0. ALAmE.

SPARK PLUG. APPLICATION FILED JULY 18,1916.

Patented Oct. 14,1919.

WILLIAM r. Laueneeu Ann GATE-THIRD re LAN earner G. ALARIE, OFTRGY, NEW?YORK, ASSIG-NORS 01E Hil -ill. A. LEE, OF TROY, NEW YORK.

itpecification of JtcttersPatent.

Application filed July 1%, 1916. Serial No. 109,874.

To all whom it may concern:

Be it known that we, Winonar l LAUGH RAN and FRANK C. Amara, citizens Orthe United States, residing at Troy, county of to efiectivel test theaction of a s arlr lu a while-in use.

Figure 1' of the drawings is a view in side elevation of a sparlcplugembodying our invention.

Fig. 2 is a central cross-section taken through the axis of the plug.

wire-holder outside Referring to the drawings wherein the invention isshown in preferred form, 1, is a wire-holder of porcelain or otherinsulating material containing two Wires 2 and 3, terminating inadjacent points at the inner end oi the sing at e.

The wirei mounted within a casing eeve and a bushing sleeve 6, scr theouter end of the sleeve 5.

The inner en T of the sleeve is screwthreeded a similarly threaded.sparkplug-apertui an engine-casing 8, in connectionwith the cound side9, of an electrlc circuit,

The colder an annular shoulder 10, which seugaged bushing 6, to securelyclamp the wire-holder in position within the wire-holder-casing.

' The wire 2, extends entirely through the Wire-holder 1, and has anoutwardly proj ecting end 11, adapted to he connected with the otherside 12, of said electric circuit.

The wire 3, extends only part-way longitudinally through thewire'holder, and has its outer end 13, projecting laterally through, andexposed upon one side of, the

of the wire-holdercasing.

A metal sleeve 14 is slidably mounted upon the wire-holder 1, outside ofthe wireholder-casing, and in contact with. the laterally projecting end13 of the wire 3.

The sleeve 14, has a handle 15, fixed thereon, whereby it can be adjustably moved toward and from the bushing 6, forming part of thewire-holder-casing, which adustment may be accomplished by a directmovement of the sleeve longitudinally of the wirel1older, or by a spiralmovement of the sleeve.

The sleeve has on its inner end a contactpoint 16, which can by suchadjustment of the sleeve be brought into contact or engagement with thebushing 6, or more or less separated from the bushing 6;

In the normal operation of the plug the sleeve 14-, is adjusted with itscontact-point 16, hearing against the bushing 6, thus electricallyconnecting the wire 3, through the sleeve 14, bushing 6 and sleeve 5,with the engine casing 8, which is in electrical connection with theground side 9, of the electric circuit. 7

When it'is desired to test the action of the plug, the sleeve 14, ismoved slightly outward, along the wire-holder 1, until its contact-point16, is slightly separated from the bushing 6, whereupon if the plu is inproper workin condition a spark will be seen between lie contact-point16, and the bushing 6. If no spark passes, it indicates that no spark isbeing formed between the wire points at 4. It will be seen that thepassage of the electric current is thus tested on the ground side of thecircuit with respect to the points 4, so that the presence of a sparkbetween the point 16 of the sleeve 14, and the bushing 6, indicates thatthe current has jumped over the gap between the points 4, maklng a morecertain test than where the test is made on the positive side of thecircuit, with respect to the points 1, in which latter case variousshort-circuits to ground would permit the current to pass the testingdevice without passing between the pointsat 4.

What we claim as new and desire to secure by Letters Patent is:

A spark-plug comprising a wire-holder of insulating material; a metalcasing for the inner portion of the wire-holder adapted to engage aspark-plug-aperture in an enginecasi'ng in' electrical connection withthe ground side of an electric circuit; two wires in said wire-holder,terminating in adjacent points at the inner end of the plug, one of saidwires extending longitudinally through the holder and having anoutwardly pro- ;Patclnted @ct. 1d, 1919.

jectin end adapted to be connected with the ot er side oi said. electriccircuit, the other of said-wires having, its outer end pro j ectinglaterally through, and being exposed upon one side of the Wire-holderoutside of said wire-holder-casing; and a metal sleeve movably mountedin contact with said laterally projecting exposed end of said lastnamedwire on the wiredwidee omeide of said wire-holder-casing, and movableinto 11) and out of contact withseid metal-causing. In testimony whereofWe have hereunto set'our hands this 10th day oi July, 1916.

WILLIAM F, LAUGHEAN. FRANK. o. Amem.

